Methods and apparatus for calibration of power converters

ABSTRACT

Methods and apparatus for a power regulator according to various aspects of the present invention may comprise a sensor adapted to generate a measurement of a voltage or a current. A memory may store a correction parameter that corresponds to the measurement, and a correction system may be adapted to adjust the measurement according to the correction parameter.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional PatentApplication No. 61/312,163, filed Mar. 9, 2010, and incorporates thedisclosure of such application by reference.

BACKGROUND OF INVENTION

Regulated power supplies typically supply voltage and current toelectrical systems, such as microelectronic devices. The regulated powersupply delivers power from a primary source to an electrical load at thespecified current, voltage, and power efficiency. Many systems useswitching power converters (SPCs) due to their high efficiency, highcurrent capability, and topology flexibility. In addition, SPCs can bedesigned to provide the very precise voltage and current characteristicsrequired by devices such as microprocessors, microcontrollers, memorydevices, and the like.

Power requirements for various applications, such as emerging leadingedge technology microprocessors, have become very difficult to satisfy.As the speed and integration of microprocessors increases, the demandson the power regulation system increase. In particular, as gate countsincrease, the power regulation current demand increases, the operatingvoltage decreases, and transient events (e.g., relatively large voltagespikes or droops at the load) typically increase in both magnitude andfrequency. Some emerging microprocessors are expected to run on lessthan 1.3 volts and more than 100 amperes.

SPC's utilizing step-down multi-phase buck converters have been thepreferred topology to meet the low voltage and high current requirementsof microprocessors. With the advent of increasingly complex powerregulation topologies, digital techniques for power converter control,specifically in multiphase designs, can improve precision and reduce thesystem's total parts count while also supporting multiple applicationsin the same power system through digitally programmable feedbackcontrol.

Existing feedback controls have taken voltage measurements from theload, as well as from the individual output phases. The feedbackinformation has been used to adjust the width of the pulses produced byeach of the phases of a multi-phase buck regulator system to bring thesupplied voltage and current within the load line tolerances specifiedby the microprocessor manufacturer. Active Transient Response (ATR) hasbeen used for high frequency response to rapidly changing powerrequirements at the load by quickly activating multiple phases to supplyor drain (as the case requires) more current to or from the load,thereby temporarily overriding the generally slower overall voltageregulator system response.

The measurement of load current is important for meeting microprocessorpower requirements that specify a load line and active voltagepositioning by defining narrow parameters within which current must besupplied at a specified voltage. In addition, leading edgemicroprocessors may specify current levels that must not be exceeded toavoid damage. To measure current, conventional systems use trimmedcurrent sense circuitry and tight component tolerance to enhanceaccuracy. The solution offers limited accuracy, however, because theinherent errors accumulate over multiple sources and are not completelyaccounted for.

SUMMARY OF THE INVENTION

Methods and apparatus for a power regulator according to various aspectsof the present invention may comprise a sensor adapted to generate ameasurement of a voltage or a current. A memory may store a correctionparameter that corresponds to the measurement, and a correction systemmay be adapted to adjust the measurement according to the correctionparameter.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete understanding of the present invention may be derived byreferring to the detailed description and claims when considered inconnection with the following illustrative figures. In the followingfigures, like reference numbers refer to similar elements and stepsthroughout the figures.

FIG. 1 is a block diagram of a test system coupled to a voltageregulator.

FIG. 2 is block diagram of a test system coupled to a voltage regulator.

FIG. 3 is a block diagram of a test system.

FIG. 4 is a flow diagram for an exemplary method for establishingcorrection parameters for the voltage regulator.

FIG. 5 is a flow diagram for an exemplary method of a voltage regulatoroperating with correction parameters.

Elements and steps in the figures are illustrated for simplicity andclarity and have not necessarily been rendered according to anyparticular sequence. For example, steps that may be performedconcurrently or in different order are illustrated in the figures tohelp to improve understanding of embodiments of the present invention.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

The present invention may be described in terms of functional blockcomponents and various processing steps. Such functional blocks may berealized by any number of hardware or software components configured toperform the specified functions and achieve the various results. Forexample, the present invention may employ various resistors,transistors, capacitors, inductors, digital logic circuits, drivercircuits, voltage supplies, measurement sensors, and the like, which maycarry out a variety of functions. In addition, the present invention maybe practiced in conjunction with any number of circuits and systems, andthe power regulator described is merely one exemplary application forthe invention. Further, the present invention may employ any number oftechniques for digital calibration, generating voltages, measuringcurrents, generating signals, and the like, such as disclosed in U.S.Pat. No. 7,262,628 to Southwell et al.

Various representative implementations of the present invention may beimplemented in conjunction with a power regulator and a test system. Thepower regulator may comprise any suitable converter for supplying powerto a load, such as a converter using step-down, step-up, buck, boost,buck-boost, forward, flyback, half-bridge, full-bridge, and/or SEPICtopologies.

Referring to FIG. 1, in one embodiment, the power regulator 100 maycomprise a controller with a power stage 110, a sensor 120 adapted tomeasure a voltage or a current, a correction system 130 adapted toadjust the measured voltage or current by a correction parameter, and amemory 140 adapted to store a correction parameter. The power regulator100 may further comprise a test interface 150 that is configured tointerface with a test system 160 and write the correction parameter tothe memory 140.

For example, referring to FIG. 2, the power regulator may comprise amultiphase power regulator 200, such as a buck converter configured tostep down a first DC voltage to a lower DC voltage, configured tooperate in conjunction with a test system 280. The multiphase powerregulator 200 may generate a switching waveform or square wave that isfiltered to provide a relatively smooth output. In one embodiment, thepower regulator 200 comprises a multiphase controller 210 and one ormore power stages 260, 270. Feedback signals allow the output voltage tobe regulated by controlling the duty cycle of the waveform. Because thepower stage is fully switched (i.e., the power stages 260, 270 are fullyoff or on), there is little loss in the power stage and the converterefficiency is high. While the exemplary embodiment is discussed inconjunction with a buck converter, various aspects of the presentinvention may be practiced in conjunction with other suitable powerregulators, including switching regulator topologies.

The controller 210 and power stages 260, 270 may be implemented in anyappropriate manner, such as one or more ICs, as discrete components, asa single integrated unit, or the like. The multiphase power regulator200 may comprise a DC-DC converter to provide power to a DC load 99comprising one or more circuits, such as a microprocessor or other load,and may comprise any appropriate systems and components to provide powerto the load 99 and perform calibration.

The power stages 260, 270 control the power supplied to the load 99according to signals from the controller 210. The power stages 260, 270may form a set of phases, and each phase may be controlled to supplypower to the load 99. For example, the power stages 260, 270 maycomprise switches connected to a power source and a sink (such asground), and the switches may be switched on and off to alternatelyconnect the load to the power source and the sink or place the powerstage in a high impedance state. The power stages 260, 270 may compriseany appropriate power stages, such as conventional MOSFET-based drivercircuits for a power regulator, including power MOSFETs, synchronousMOSFETs, output inductors, and/or output capacitors.

In one embodiment, the power regulator 200 comprises one or more currentsensors 261, 271 to configured to provide the controller 210 with anoutput current. The current sensors 261, 271 may be adapted to measurethe output current of each power stage 260, 270 and to generate anoutput current signal corresponding to the measured output current. Theoutput current signal may be provided to the controller 210 as feedback.

The current sensors 261, 271 may be implemented in any suitable mannerto measure current, and may comprise any appropriate components, such asconventional active or passive current sensor circuits. For example, inone embodiment, the current sensors 261, 271 comprise conventionalcurrent sensors configured to sense the output current through thevoltage across an output inductor (e.g., DCR current sense), voltageacross a transistor in the power stage 260, 270 (e.g., RDSon), a currentmirror of one or more transistors in power stage 260, 270 (e.g., currentmirror), or voltage across a resistor in series with the input, output,or ground return (e.g., shunt resistor). The current sensors 261, 271may further comprise additional circuitry to provide gain, offset,clamping, filtering, or other processing that generates a measuredcurrent signal to the controller that corresponds to the measuredcurrent.

In one embodiment, the controller 210 is configured to control theoutput of the power stages 260, 270 to regulate an output voltagesupplied to the load 99. The controller 210 may control the power stages260, 270 in any suitable manner, such as according to conventional pulsewidth modulation techniques, pulse frequency modulation techniques, orother suitable control processes. The controller 210 may comprise analogcomponents, digital components, or a combination of analog and digitalcomponents. The controller 210 may operate in response to any suitableinputs and parameters, such as reference signals, current feedback,voltage feedback, target output voltage and/or current.

In one embodiment, the controller 210 is configured to receive ameasured current signal from the power stages 260, 270. In oneembodiment, the controller 210 is configured to modify its responseaccording to the output current. In one embodiment, the controller 210modifies the measured current signal according to a correction parameterin order to account for an inaccuracy in the measured current signal.

In one embodiment, the controller 210 comprises a pulse width modulator(PWM) circuit 220 configured to generate pulse width modulated signalsthat control a duty cycle of the power stages 260, 270 such that theDC-DC voltage conversion meets the target output voltage. The controller210 may respond to feedback signals, such as feedback signalscorresponding to output current and/or output voltage, load lines,transient control, adaptive voltage positioning, and the like. Forexample, in many DC-DC converters, the output current may be determinedwith precision, so that the converter can perform functions such ascurrent monitoring, telemetry, limiting, and adaptive voltagepositioning (load line or droop resistance).

In one embodiment, the controller 210 operates in one or more modes. Forexample, the controller 210 may be configured to operate in variousmodes of operation comprising a mode with a variable number of phases,different modes to optimize transient response or efficiency, specialtest modes such as reduced or single phase operation, or reducedbandwidth modes to isolate measurements to a subset of the senseelements and circuitry and filter measurement noise.

The controller 210 may include any appropriate elements for controllingthe power to the load 99 via the power stages 260, 270 and interfacingwith the test system 180 for calibration. In one embodiment, thecontroller 210 comprises the pulse width modulation (PWM) circuit 220, acurrent sense circuit 230, a non-volatile memory (NVM) 240, and a testinterface 250. In one embodiment, the PWM circuit 220 drives the powerstages 260, 270, according to, among other things, signals received fromthe current sense circuit 230, which may receive the measured currentsignals from current sensors and generate signals accordingly.

In one embodiment, the PWM circuit 220 provides a duty cycle that drivesthe power stages 260, 270. The PWM circuit may comprise any suitablesystem or circuit for driving the power stages 260, 270, such as aconventional PWM controller for digital power regulator controllers. ThePWM circuit 220 may drive the power stages according to any suitablecriteria and inputs, such as a voltage and a current feedback signal,load lines, transient control, adaptive voltage positioning, and thelike. The PWM circuit 220 may also perform other functions, such ascorrection and telemetry functions. In the present embodiment, the PWMcircuit controls the signals of the power stages 260, 270 according tothe current feedback signal, for example received via the current sensecircuit 230, and output voltage feedback (not shown).

Current and voltage feedback signals may be provided to the PWM circuit220 and/or other elements of the controller 210 in any suitable manner.In one embodiment, the correction system 130 is adapted to adjustmeasured current and voltage measurements and provide the adjustedsignals to the PWM circuit 220. In one embodiment, the correction system130 is adapted to retrieve a stored correction parameter from a memory.The correction system may be independently implemented, integrated intothe controller 210, a sensor, the current sense circuit 230, or anyother suitable element or location.

In one embodiment, the current sense circuit 230 receives the measuredcurrent signals from the current sensors 261, 271 and transmits thecurrent feedback signal to the PWM circuit 220 and/or other elements ofthe controller 210. The current sense circuit 230 may generate an analogor digital representation of the current based upon the measured currentsignals received from the current sensors 261, 271. In one embodiment,the current sense circuit 230 receives output current measurements fromthe current sensors 261, 271 in the power stages 260, 270, and transmitsraw or adjusted output current measurement to other systems, such as thetest interface 250 and the PWM circuit 220.

In addition, in one embodiment, the current sense circuit 230 is coupledto the NVM 240, for example to read correction parameters from the NVM240. In one embodiment, the current sense circuit 230 may perform one ormore functions of the correction system 130, such as adjusting themeasured current according to the correction parameters, and theadjusted current measurement may be provided to the various systems,such as the PWM circuit 220 and/or the test interface 250.Alternatively, in one embodiment, the current sense circuit 230transfers raw output current signals to the PWM circuit 220, such as bymultiplexing the signals from the current sensors 261, 271. The PWMcircuit 220 or other system may perform one or more functions of thecorrection system 130, such as retrieving the correction parameters fromthe NVM 240 and adjusting the measured current output accordingly.

The controller 210 may include a memory configured to the storecorrection parameters to be used by the controller 210 to compensate forerrors or variations that affect the measured output current, such aserrors associated with the current sensors 261, 271, the controller 210,or the load 99. The memory may be accessed by any appropriate systems,such as the test interface 250, the PWM circuit 220, and the currentsense circuit 230. The memory may also store other data in addition tothe correction parameters. The memory may comprise any appropriatememory element for storing data. In the present embodiment, the memorycomprises the NVM 240. The NVM 240 may comprise a memory that retainsstored information even when not powered.

The test interface 250 provides an interface between the test system 280and the regulator 200. The test interface 250 may facilitateimplementing test processes, monitoring the operation of the regulator200 in response to the test processes, reading the sensed current outputfrom the current sense circuit 230, and/or reading and storingcorrection parameters in the NVM 240. The test interface 250 also mayallow the test system 280 to control the mode of operation of themultiphase power regulator 200 as well as the current provided by themultiphase power regulator 200 to the load 99.

The test system 280 tests the regulator 200, for example to test and/orto adjust the operation of the regulator 200. The test system 280 maycomprise any appropriate system for testing the regulator, such as acomputer programmed to at least partially control the operation of theregulator 200 and measure the output and/or other performancecharacteristics of the regulator 200. For example, referring to FIG. 3,the test system 280 may comprise a regulator interface 288 to transmitsignals to and from the regulator 200. The test system 280 may furthercomprise a test controller 282, a monitoring system 284, and acalculation system 286. The test controller 282 generates test signalsto be applied to the regulator 200, for example to control the operationof the regulator 200. The monitoring system 284 monitors the operationof the regulator 200, such as by monitoring the output and other signalsof the regulator 200 in response to the test signals applied by the testcontroller 282. The calculation system 286 calculates correctionparameters to compensate for errors associated with the regulator 200.

The test controller 282, monitoring system 284, and calculation system286 may be implemented as multiple systems or integrated into a singlesystem. For example, the test controller 282, monitoring system 284, andcalculation system 286 may be implemented via a single computerprogrammed to apply test signals to the regulator 200, measure andprocess the response of the regulator 200, and compute correctionparameters for detected errors in the regulator 200. Alternatively, oneor more of the various systems of the test system 280 may be integratedwith other systems or separated into multiple discrete devices. In oneembodiment, the test system 280 may take current measurements inmultiple modes of operation, determine the accuracy of the outputcurrent measurements made by the multiphase power regulator 200 in eachmode of operation, and provide the controller 210 with correctionparameters, such as for each mode of operation. The correctionparameters may be stored in the NVM 240 and used by the regulator 200 tomore accurately measure and/or control the multiphase power regulator's200 output.

The regulator interface 288 facilitates transmission of signals betweenthe test system 280 and the regulator 200. The regulator interface 288may comprise any suitable interface, for example comprising physical andelectrical connections for connecting the test system 280 to theregulator 200. In the present embodiment, the regulator interface 288 isadapted to connect to the output of the regulator 200, for example tomeasure the voltage and/or current output to the load, and to the testinterface 250 of the controller 210. The regulator interface may,however, provide any appropriate connections for controlling theregulator 200 and/or monitoring the response of the regulator 200.

The monitoring system 284 may receive information from the regulator 200for testing. For example, the monitoring system 284 may comprise amemory, such as one or more registers, buffers, random access memory, orthe like, coupled via the regulator interface 288 to the regulator 200,such as at the output of the power stages 260, 270 and the output of thecurrent sense circuit 230. The monitoring system 284 may accuratelymeasure the current supplied to the load 99 by the power stages 260,270, as well as the output current measured by the multiphase powerregulator 200, such as at the current sense circuit 230 and/or thecurrent sensors 261, 271. The monitoring system may, however, measure orreceive any appropriate signals corresponding to the regulator 200operation.

In the present embodiment, the monitoring system 284 measures thevoltage and/or current provided to the load 99, such as via a connectionto the output of the power stages 260, 270. The monitoring system 284 isalso connected to the test interface 250 of the controller 210. Throughthe test interface 250, the monitoring system 284 may measure the outputcurrent as measured by the regulator 200 elements and indicated by thecurrent sense circuit 230. The monitoring system 284 may measure anysuitable parameters, such as the output current of the multiphase powerregulator 200 and the output current measured by the current sensors261, 271 and/or the current sense circuit 230.

The test controller 282 operates the regulator 200 and/or supplies testsignals to the regulator 200 to test the operation of the regulator 200and allow the monitoring system 284 to gather information. The testcontroller 282 may comprise any suitable system for controlling theregulator 200 and generating the proper test signals, and may controlthe regulator 200 according to any appropriate test procedure orgenerate any suitable test signals. For example, the test controller 282may comprise a computer programmed to generate test signals according toa test program to cause the regulator 200 to operate under certaindesired conditions.

In the present embodiment, the test controller 282 may control theoutput and/or mode of the multiphase power regulator 200. For example,the test controller 182 may induce the multiphase power regulator 200 tooutput a specific voltage and/or a specific current or generate specificPWM signals. The test controller 282 may also be adapted to generate anoperating mode signal to place the multiphase power regulator 200 in oneor more different modes of operation. For example, the multiphase powerregulator 200 may be placed in a mode with a variable number of phases,different modes to optimize transient response or efficiency, specialtest modes such as reduced or single phase operation, and/or reducedbandwidth modes, such as to isolate the measurement to a subset of thesense elements and circuitry and filter measurement noise. In each mode,the monitoring system 284 may record various measurements and signals,and transfer the results to the calculation system 286.

The calculation system 286 calculates correction parameters to correctfor errors in the regulator 200, such as according to the measurementsmade by the monitoring system 284 in response to test proceduresimplemented by the test controller 282. The correction parameters may beprovided to the controller 210, which can use the correction parametersto compensate for errors in the regulator 100, such as to modify currentsense data to achieve a more accurate measurement.

The calculation system 286 may calculate the correction parametersaccording to any suitable criteria and/or algorithms. For example, ifthe monitoring system 284 of the test system 280 measures the outputcurrent of the multiphase power regulator 100 to be 10 amps and themultiphase power regulator 100 measures the output current to be 10.1amps, the calculation system 286 may provide a correction parameter thatis a linear offset of −0.1 amps. In another embodiment, the correctionparameter may be a gain, such that in the above example, the correctionparameter may comprise a gain factor of 1.01. In other embodiments, thecorrection parameter could be both a gain and an offset, or a look-uptable of correction parameters for correcting measurements underdifferent conditions. Any appropriate algorithm may be utilized forgenerating and using the correction parameters. The test system 180 maytake multiple measurements under multiple conditions, and thecalculation system 186 may create one or more correction parametersaccordingly.

The calculation system 286 may store the correction parameters such thatthe correction parameters are accessible to the regulator 200, such asin the NVM 240. During operation, the regulator 200 may access the NVM240 to retrieve the correction parameters to compensate for measurementerrors.

The test system 280 may test the accuracy of the multiphase powerregulator 200 and generate correction parameters based on the tests. Thetest system 280 may test the regulator 200 according to any suitabletest procedure to identify characteristics of the regulator 200, such asto identify errors in measurements from the current sensors 261, 271,current sense circuit 230, or other elements. In various embodiments,the test system 280 may make several measurements to determine thecurrent sense accuracy. The test system 280 may generate correctionparameters and interface with the controller 210 to store the correctionparameters in the NVM 240. The correction parameters may be calculatedand applied to minimize the current sense error, for example due tocontributions from both the current sense elements in the power stageand the current sense circuitry in the controller.

Generally, the test system 280 may interface with the controller 210 tomake measurements and monitor controller telemetry while controlling theload current such that measurements can be made to accurately determinethe current sense error. The test system 280 may further compute andstore current sense parameters that allow current sense errors to becompensated (e.g., offset and gain error). The test system 180 may storethe correction parameters in the controller 210 to achieve high currentsense accuracy.

The correction parameters allow the current sense accuracy of themultiphase switched power converter to be improved beyond the accuracyof the individual current sense elements and circuitry. Implementationof the correction parameters via the test system 280 addresseschallenges associated with improved accuracy of current sense inmultiphase switched power converters for adaptive voltage positioning,efficiency measurement and optimization, and telemetry in the presenceof component tolerance, mismatch, and temperature drift in the senseelements and circuitry.

For example, referring to FIG. 4, a test procedure (300) according tovarious aspects of the present invention comprises placing thecontroller 210 in a measurement mode to facilitate measurements, such ascurrent sense measurements (310). The controller 210 may operate indifferent modes, such as in response to signals from the test system280. The measurement mode may comprise a standard operational mode or aspecial test mode. While in measurement mode, the test system 280 mayactively control the operation mode of the controller 210, control theoutput voltage/current, and/or passively monitor the multiphase powerregulator's 200 operational characteristics. The test system 280 maylikewise be placed in a testing mode, such as a current sensemeasurement mode to allow for current sense accuracy measurements (230).

The test system 280 may identify errors in measurements by the regulator200 components. For example, the test system 180 may read telemetryinformation from the controller 210 and compare the telemetryinformation with nominal data, such as measurements made by the testsystem 280 or known values, to determine the current sense error (330).The test system 280 may take multiple measurements in one or moreoperating modes, for example to determine the accuracy of the currentmeasurements by the current sensors 261, 271 and/or the current sensecircuit 230. For example, in one embodiment, the test system 280 mayforce a known load current through a test terminal and then read thecurrent telemetry from the controller 210. The test system 280 may thentake several measurements at various load currents and store the resultsof each test, such as in a memory in the test system 280.

After the test system 280 has measured the current sense error for thepresent mode of operation, the test system 280 may determine if thereare additional modes to measure (340). For example, the different modesof operation may also include a static mode, such as a constant outputcurrent, a differential mode, such as a voltage differential, a loadedor unloaded mode, a dynamic load, such as a varying output current, adifferent operational mode, a special test mode, such as activating asingle phase at a time, and enhanced accuracy mode. Steps 310 through340 may then be repeated for each operating mode or other condition formeasuring the performance of the regulator 200.

In one embodiment of a mode of operation, the test system 280 may forcethe output voltage directly and measure the load current. For example,if the load is a CPU motherboard with the CPU plugged in, the testsystem 280 may force an output voltage and measure the CPU current whilethe CPU is in a low current or off state, allowing for the determinationof the CPU's leakage current. In another mode, the test system 180 maychange the load current in a pre-determined dynamic manner that allowscurrent measurements under different conditions to be made.

After each mode of operation has been tested, the test system 280 maycalculate the correction parameters (330) and store the correctionparameters, such as in the NVM 240 (350). The correction parameters maycomprise an offset and/or gain adjustment for each mode of operation, anoffset and/or gain adjustment for each power stage or phase, or alook-up table that provides non-linear correction of the current sensetransfer function.

The power regulator 200 may use the correction parameters in normaloperation (as opposed to a testing mode), such as when the powerregulator is no longer connected to the test system 280 and is deployedto provide power to a load. When measurements or other data are receivedor generated, the controller 210 may access the NVM 240 and retrieve therelevant correction parameters. The controller 210 may adjust themeasurements by applying the correction parameters to the measurementsor other data to compensate for known errors, thus improving theaccuracy of the power regulation and/or other characteristics.

For example, the output current value supplied to PWM circuit 220 in thepresent embodiment is the current measured by the current sensors 261,271. The controller 210 may adjust the data from the current sensors261, 271 according to the correction parameters retrieved from the NVM240. This allows the current sense accuracy to be improved beyond theaccuracy of the individual current sense elements and circuitry and forPWM circuit 220 to receive higher accuracy load current measurement.

Referring to FIG. 5, an operation process 400 may include adjusting themeasurements according to correction parameters stored in the NVM 240.For example, the current sensors 261, 271 may measure the output currentof the power stages 260, 270 (410). The controller 210 may determine thecontroller's 210 present output mode (420). For example, if themultiphase power regulator 200 is operating with all phases active and asteady output current, then the controller may recognize that all phasesare active and the output is steady. In another case, if the multiphasepower regulator 200 is operating in a low-power mode comprising only oneactive phase, then the controller 200 would determine it is in alow-power mode.

The controller 210 then retrieves a correction parameter for the presentoutput mode that is stored in the NVM 240 (430). For example, if onlyone phase of the multiphase power regulator 200 is active, then thecorrection parameter for that single phase is retrieved. In anothercase, if the multiphase power regulator 200 is operating with a steadyoutput current and all phases active, then one or more the correspondingcorrection parameters may be retrieved.

The current that is measured by the current sensors 261, 271 may bemodified by the controller 110 according to the correction parameter(440). For example, if the correction parameter comprises an offset of+0.1 amps and the measured current is 3 amps, then the controller 210may adjust the measured current to be 3.1 amps. The adjusted currentmeasurement is then provided to the PWM circuit 220 (450). The PWMcircuit 220 then provides the appropriate duty cycle to the power stages260, 270 so as to provide the correct output voltage.

In the foregoing specification, the invention has been described withreference to specific exemplary embodiments. Various modifications andchanges may be made, however, without departing from the scope of thepresent invention as set forth in the claims. The specification andfigures are illustrative, rather than restrictive, and modifications areintended to be included within the scope of the present invention.Accordingly, the scope of the invention should be determined by theclaims and their legal equivalents rather than by merely the examplesdescribed.

For example, the steps recited in any method or process claims may beexecuted in any order and, unless otherwise noted, are not limited tothe specific order presented in the claims. Additionally, the componentsand/or elements recited in any apparatus claims may be assembled orotherwise operationally configured in a variety of permutations and areaccordingly not limited to the specific configuration recited in theclaims.

Benefits, other advantages and solutions to problems have been describedabove with regard to particular embodiments; however, any benefit,advantage, solution to problem or any element that may cause anyparticular benefit, advantage or solution to occur or to become morepronounced are not to be construed as critical, required or essentialfeatures or components of any or all the claims.

As used herein, the terms “comprise”, “comprises”, “comprising”,“having”, “including”, “includes” or any variation thereof, are intendedto reference a non-exclusive inclusion, such that a process, method,article, composition or apparatus that comprises a list of elements doesnot include only those elements recited, but may also include otherelements not expressly listed or inherent to such process, method,article, composition or apparatus. Other combinations and/ormodifications of the above-described structures, arrangements,applications, proportions, elements, materials or components used in thepractice of the present invention, in addition to those not specificallyrecited, may be varied or otherwise particularly adapted to specificenvironments, manufacturing specifications, design parameters or otheroperating requirements without departing from the general principles ofthe same.

What is claimed is:
 1. A method of operating a regulator, comprising:measuring at least one of a voltage and a current of the regulator;retrieving from a memory a correction parameter that compensates forerrors or variations affecting the measurement; adjusting themeasurement according to the correction parameter; and regulating anoutput of the regulator according to the adjusted measurement, whereinregulating the output of the regulator according to the adjustedmeasurement comprises: providing the adjusted measurement to a PWM(pulse width modulation) circuit; and adjusting a duty cycle of a powerstage of the regulator via the PWM circuit responsive to the adjustedmeasurement.
 2. A method of operating a regulator according to claim 1,wherein measuring the at least one of the voltage and the current of theregulator comprises measuring the current output of the regulator inconjunction with a current sensor exhibiting an error, and wherein thecorrection parameter compensates for the error of the current sensor. 3.A method of operating a regulator according to claim 1, furthercomprising determining an output mode of the regulator.
 4. A method ofoperating a regulator according to claim 3, wherein the correctionparameter retrieved from the memory also corresponds to the output modeof the regulator.
 5. A method of operating a regulator according toclaim 4, wherein adjusting the measurement according to the correctionparameter comprises offsetting a measured voltage by a voltage offset.6. A method of operating a regulator according to claim 4, whereinadjusting the measurement according to the correction parametercomprises offsetting a measured current in a first phase by a firstcurrent sense offset.
 7. A method of operating a regulator according toclaim 6, wherein adjusting the measurement according to the correctionparameter comprises offsetting a measured current in a second phase by asecond current sense offset.
 8. A method of operating a regulatoraccording to claim 4, wherein adjusting the measurement according to thecorrection parameter comprises offsetting a measured current by a gainadjustment for the output mode of the regulator.
 9. A method ofoperating a regulator according to claim 4, wherein adjusting themeasurement according to the correction parameter comprises offsettingat least one of a measured voltage and a measured current by a value ina lookup table comprising a plurality of non-linear corrections.
 10. Amethod of operating a regulator according to claim 1, wherein thecurrent of the regulator is measured and the correction parameterretrieved from the memory minimizes a current sense error associatedwith measuring the current of the regulator.
 11. A method of operating aregulator according to claim 1, wherein the correction parameter allowsa current sense accuracy of the regulator to be improved beyond anaccuracy of individual current sense elements and circuitry used tomeasure the current of the regulator.